Thiophosphates

ABSTRACT

Thiophosphates of the formula ##EQU1## where X is O or S, R is a hydrocarbon or a substituted hydrocarbon group such as alkyl, aryl, cycloalkyl, alkaryl, aralkyl, etc., and R&#39; is a 3-thione-propene-1 or a substituted 3-thione-propene-1 group; the preparation thereof by reacting a 1,2-dithiolium compound with a phosphite ester; the reversion to the original dithionium compound is effected by reacting the thiophosphate under acid conditions; and the uses of such thiophosphates as corrosion inhibitors in acid systems.

This invention relates to S-(3-thione-propene-1) thiophosphates, thepreparation thereof, and uses therefor.

1,2-DITHIOLE-3-THIONES ARE KNOWN COMPOUNDS PREPARED BY A VARIETY OFMETHODS. Examples of such compounds, and methods for their preparation,are disclosed in THE CHEMISTRY OF HETEROCYCLIC COMPOUNDS, "Multi-Sulfurand Sulfur and Oxygen Five-and Six-Membered Heterocycles," PART 1, pages237-386, by David S. Breslow et al., Interscience Publishers, 1966.

1,2-DITHIOLE-3-THIONES MAY BE EXPRESSED BY THE FORMULA: ##EQU2## where Rand R' are substituted groups, for example, alkyl, aryl, cycloalkyl,alkenyl, alkynyl, alkaryl, aralkyl, heterocyclic, etc. In addition, oneof the above R's may be hydrogen. Examples of a wide variety of1,2-dithiole-3-thiones are presented in the above text by Breslow et alin Table 4, pages 352-366, which is incorporated into this applicationas if part hereof.

1,2-DITHIOLE-3-THIONES ARE CONVENIENTLY PREPARED BY THE CLASSIC METHODOF REACTING AN OLEFIN WITH SULFUR, FOR EXAMPLE, ACCORDING TO THEFOLLOWING EQUATION: ##EQU3##

The olefin employed in the reaction contains

1. a reactive double bond

2. a primary carbon atom

3. at least four hydrogen atoms on the 3 terminal carbons with at leastone hydrogen on the carbon beta to a primary carbon atom

This reaction is carried out at any suitable temperature and time, forexample, at about 100° to 300°C., such as from about 140° to 240°C. butpreferably from about 160° to 220°C. for a period of about 2 to 160hours, and about 10 to 50 hours, but preferably about 15 to 40 hours.

The following examples are presented by way of illlustration and not oflimitation to show the preparation of 1,2-dithiole-3-thiones which maybe employed as starting materials to prepare the dithiolium compounds ofthis invention.

EXAMPLE 1A The Preparation of 4-phenyl- 1,2-dithiole- -dithiole--thione

In a suitable reactor equipped with a stirrer, thermometer and a refluxcondenser, was placed 118 g of methyl-styrene and 48 g of sulfur. Themixture was heated for 37 hours at 220°-210°C. After the reaction wascompleted, the mixture was slowly cooled to room temperature. Theproduct was collected and crystallized from benzene, red crystals, (32grams, 50% yield), m.p. 122°-124°C.

EXAMPLE 2A Preparation of 4-(3-methoxy-4-hydroxy)phenyl-1,2-dithiole-3-thione

In a suitable reactor equipped with a stirrer, thermometer, additionfunnel and reflux condenser was placed 32 g of sulfur, 1.0 g ofdi-o-tolylguanidine as catalyst and 150 cc of mesitylene as solvent. Themixture was brought to a reflux (170°C.) and over a 1 hour period 66 gof isoeugenol ##SPC1##

was added dropwise. Reflux was continued for 48 more hours. Themesitylene was decanted from the solid. The solid was treated twice with500 cc portion of a 5% aqueous potassium hydroxide solution. Uponacidification the product precipitated as a brown solid.

EXAMPLE 3A Preparation of 4-neopentyl- 5-t-butyl-1,2-dithiole-3-thione

To a mixture of 320 g of sulfur and 6.0 g of di-o-tolylguanidine wasadded over a 9 hour period, at a reaction temperature of 210°-215°C.,336 g of triisobtylene.

Mainly ##EQU4## Heating at 210°-215°C, was continued for an additional14 hours. The product was distilled and there was collected 220 g of4-neopentyl-5-t-butyl-1,2-dithiole-3-thione, b.p. 155°-185°C. (3-4 mmHg). ##EQU5##

EXAMPLE 4A Preparation of 4,5-tetramethylene-1,2-dithiole-3-thione

In a suitable reactor equipped with a stirrer, reflux condenser,thermometer and addition funnel was placed 24 g of sulfur, 171 g ofcarbon disulfide and 150 cc of dimethyl formamide. The mixture wascooled to 0°C. and under continuous stirring and cooling 132 g of1-morpholino-1cyclohexene was introduced over a 1/2 hour period. Afterthe addition was completed, stirring was continued for an additional 16hours. The resulting slurry was poured into water and the resultingorange solid crystallized from acetone, m.p. 95°-97°C. Yield 37%.

The following table presents illustrative 1,2-dithiole-3-thiones of theformula ##EQU6## The radical indicated replaces the H's in the fourthand/or fifth positions as indicated.

                                      TABLE I                                     __________________________________________________________________________    1)     4-CH.sub.3                                                             2)     5-CH.sub.3 --                                                          3)     4-C.sub.2 H.sub.5 --                                                   4)     5-C.sub.2 H.sub.5 --                                                   5)     4-(CH.sub.3).sub.3 CCH.sub.2 --                                        6)     5-n-C.sub.17 H.sub.35 --                                               7)     4-C.sub.6 H.sub.5 --                                                   8)     5-C.sub.6 H.sub.5 --                                                   9)     4-(p-CH.sub.3 C.sub.6 H.sub.4 --)                                      10)    5-(p-CH.sub.3 C.sub.6 H.sub.4 --)                                      11)    4-(p-C.sub.2 H.sub.5 C.sub.6 H.sub.4 --)                               12)    4-(p-t-C.sub.4 H.sub.9 C.sub.6 H.sub.4 --)                             13)    4-(p-t-C.sub.5 H.sub.11 C.sub.6 H.sub.4 --)                            14)    5-(p-C.sub.6 H.sub.5 --C.sub.6 H.sub.4 --)                             15)    5-(p-ClC.sub.6 H.sub.4 --)                                             16)    5-(p-BrC.sub.6 H.sub.4 --)                                             17)    5-(p-IC.sub.6 H.sub.4 --)                                              18)    4-(p-CH.sub.3 OC.sub.6 H.sub.4 --)                                     19)    5-(o-CH.sub.3 OC.sub.6 H.sub.4 --)                                     20)    5-(p-CH.sub.3 OC.sub.6 H.sub.4 --)                                     21)    5-(p-HOC.sub. 6 H.sub.4 --)                                            22)    5-(p-CH.sub.3 CO.sub.2 C.sub.6 H.sub.4 --)                             23)    5-[p-(CH.sub.3).sub.2 NC.sub.6 H.sub.4 --]                             24)    5-[2,4-(CH.sub.3).sub.2 C.sub.6 H.sub.3 --]                            25)    5-(2-CH.sub.3 O--5-CH.sub.3 C.sub.6 H.sub.3 --)                        26)    5-[2,3-(CH.sub.3 O).sub.2 C.sub.6 H.sub.3 --]                          27)    5-[2,5-(CH.sub.3 O).sub.2 C.sub.6 H.sub.3 --]                          28)    5-[3,4-(CH.sub.3 O).sub.2 C.sub.6 H.sub.3 --]                          29)    5-(3-CH.sub.3 O--4-HOC.sub.6 H.sub.3)                                  30)    5-(2-HO--3-CH.sub.3 OC.sub.6 H.sub.3 --)                               31)    5-(3-CH.sub.3 O--4-CH.sub.3 O.sub.2 CCH.sub.2 OC.sub.6 H.sub.3                --)                                                                    32)    5-[3,4-(HO).sub.2 C.sub.6 H.sub.3 --]                                  33)    5-[3,4-(CH.sub.3 CO.sub.2).sub.2 C.sub.6 H.sub.3 --]                   34)    5-(3,4-Methylenedioxyphenyl-)                                          35)    5-(3,4,5-I.sub.3 C.sub.6 H.sub.2 --)                                   36)    4-(1-Naphthyl-)                                                        37)    4-(1-Naphthyl-)                                                        38)                                                                           39)                                                                           40)    5-(2-Furyl-)                                                           41)    4-(2-Thienyl-)                                                         42)    5-(2-Thienyl-)                                                         43)    4-(4-CH.sub.3 --2-thienyl-)                                            44)    5-(5-CH.sub.3 --2-thienyl-)                                            45)    5-(5-C.sub. 2 H.sub.5 --2-thienyl-)                                    46)    4-[3,4-(CH.sub.3).sub.2 --2-thienyl-]                                  47)    5-(2-Pyridyl-)                                                         48)    5-(3-Pyridyl-)                                                         49)    5-(4-Pyridyl-)                                                         50)    5-(C.sub.6 H.sub.5 CH=CH--)                                            51)    5-(p-CH.sub.3 OC.sub.6 H.sub.4 CH=CH--)                                52)    5-(2-Furyl-CH=CH--)                                                    53)    5-[p-(CH.sub.3).sub.2 HC.sub.6 H.sub.4 N=CH--]                         54)    5-[p-(CH.sub.3).sub.2 NC.sub.6 H.sub.4 N=CH--]                         55)    5-C.sub.2 H.sub.5 OOC                                                  56)    5-HOOC--                                                               57)    4,5-(CH.sub.3 --).sub.2                                                58)    4-CH.sub.3 --5-C.sub.2 H.sub.5 --                                      59)    4-C.sub.2 H.sub.5 --5-CH.sub.3 --                                      60)    4,5-(C.sub.2 H.sub.5 --).sub.2                                         61)    4-(n-C.sub.3 H.sub.7 --)-5-CH.sub.3 --                                 62)    4-(n-C.sub.4 H.sub.9 --)-5-CH.sub.3 --                                 63)    4-CH.sub.3 --5-(t-C.sub.4 H.sub.9 --)                                  64)    4-(CH.sub.3).sub.3 CCH.sub.2 --5-(t-C.sub.4 H.sub.9 --)                65)    4-[(C.sub.2 H.sub.5).sub.2 NCH.sub.2 CH.sub.2 --]-5-CH.sub.3 .                HClO.sub.4                                                             66)    4-[(C.sub.2 H.sub.5).sub.2 NCH.sub.2 CH.sub.2 --]-5-CH.sub.3 .                HCl                                                                    67)    4-C.sub.6 H.sub. 4 CH.sub.2 --5-CH.sub.3 --                            68)    4-CH.sub.3 --5-C.sub.6 H.sub.5 --                                      69)    4-C.sub.6 H.sub.5 --5-CH.sub.3 --                                      70)    4-C.sub.2 H.sub.5 --5-C.sub.6 H.sub.5 --                               71)    4-CH.sub.3 --5-(p-CH.sub.3 C.sub.6 H.sub.4 --)                         72)    4-CH.sub.3 --5-(p-ClC.sub.6 H.sub.4 --)                                73)    4-CH.sub.3 --5-(p-BrC.sub.6 H.sub.4 --)                                74)    4-CH.sub.3 --5-(p-IC.sub.6 H.sub.4 --)                                 75)    4-CH.sub.3 --5-(o-CH.sub.3 OC.sub.6 H.sub.4 --)                        76)    4-CH.sub.3 5-(p-CH.sub.3 OC.sub.6 H.sub.4 --)                          77)    4-(p-CH.sub.3 OC.sub.6 H.sub.4 --)-5-CH.sub.3 --                       78)    4-CH.sub.3 --5-[2,4-(CH.sub.3).sub.2 C.sub.6 H.sub.3 --]               79)    4-CH.sub.3 --5-[2,5-(CH.sub.3).sub.2 C.sub.6 H.sub.3 --]               80)    4-CH.sub.3 --5-[3,4-(CH.sub.3).sub.2 C.sub.6 H.sub.3 --]               81)    4-CH.sub.3 --5-(4-CH.sub.3 O--3-(CH.sub.3 C.sub.6 H.sub.3 --)          82)    4-CH.sub.3 --5-(2CH.sub.3 O--4-CH.sub.3 C.sub.6 H.sub.3 --)            83)    4-CH.sub.3 --5-(2-CH.sub. 3 O--5-CH.sub.3 C.sub.6 H.sub.3 --)          84)    4-CH.sub.3 --5-(2-CH.sub. 3 S--5-CH.sub.3 C.sub.6 H.sub.3 --)          85)    4-CH.sub.3 --5-(2-HO--3-CH.sub.3 OC.sub. 6 H.sub.3 --)                 86)    4-CH.sub.3 --5-[2,4-(CH.sub.3 O).sub.2 C.sub.6 H.sub.3 --]             87)    4-CH.sub.3 --5-[2,5-(CH.sub.3 O).sub.2 C.sub.6 H.sub.3 --]             88)    4-CH.sub.3 --5-[3,4-(CH.sub.3 O).sub.2 C.sub.6 H.sub.3 --]             89)    4-CH.sub.3 --5-[2,4,6-(CH.sub.3).sub.3 C.sub.6 H.sub.2 --]             90)    4-(1-Naphthyl-)-5-CH.sub.3 --                                          91)    4-(1-Naphthyl-)-5-C.sub.2 H.sub.5 --                                   92)    4-CH.sub.3 --5-(2-CH.sub.3 O--1-naphthyl-)                             93)    4-CH.sub.3 --5-(2-thienyl-)                                            94)    4-(2-Thienyl-)-5-CH.sub.3 --                                           95)    4-(5-CH.sub.3 --2-thienyl-)-5-CH.sub.3 --                              96)    4-CH.sub.3 --5-(5-CH.sub.3 --2-thienyl-)                               97)    4-C.sub.2 H.sub.5 --5-(5-CH.sub.3 --2-thienyl-)                        98)    4-(5-C.sub.2 H.sub.5 --2-thienyl-)-5-CH.sub.3 --                       99)    4-CH.sub.3 --5-(5-C.sub.2 H.sub.5 --2-thienyl-)                        100)   4-C.sub.2 H.sub.5 --5-(5-C.sub.2 H.sub.5 --2-thienyl-)                 101)   4-CH.sub.3 --5-[4,5-(CH.sub.3).sub.2 --2-thienyl-]                     102)   4-CH.sub.3 --5-(3-pyridyl-)                                            103)   4-C.sub.2 H.sub.5 --5-(3-pyridyl-)                                     104)   4-n-C.sub.4 H.sub.9 --5-(3-pyridyl-)                                   105)   4-CH.sub.3 --3-(4-pyridyl-)                                            106)   4-C.sub.2 H.sub.5 --5-(4-pyridyl-)                                     107)   4-C.sub.2 H.sub.5 --5-(C.sub.6 H.sub.5 CH=CH--)                        108)   4-CH.sub.3 --5-(p-CH.sub.3 OC.sub.6 H.sub.4 CH=CH--)                   109)   4-C.sub.2 H.sub.5 --5-(p-CH.sub.3 OC.sub.6 H.sub.4 CH=CH--)            110)   4-(-n-C.sub.3 H.sub.7 --)-5-(p-CH.sub.3 OC.sub.6 H.sub.4 CH=CH--)      111)   4-C.sub.2 H.sub.5 --5-(2-furyl-CH=CH--)                                112)   4-(n-C.sub.3 H.sub.7 --)-5-(2-furyl-CH=CH--)                           113)   4-C.sub.6 H.sub.5 --5-C.sub.6 H.sub.5 CH.sub.2 --                      114)   4-(C.sub.6 H.sub.5 CO--)-5-C.sub.6 H.sub.5 --                          115)   4-(C.sub.6 H.sub.5 CS--)-5-C.sub.6 H.sub.5 --                          116)   4,5-(C.sub.6 H.sub.5 --).sub.2                                         117)   4-(p-CH.sub.3 OC.sub.6 H.sub.4 --)-5-C.sub.6 H.sub.5 --                118)   4-(p-HOC.sub.6 H.sub.4 --)-5-C.sub.6 H.sub.5 --                        119)   4-(p-CH.sub.3 CO.sub.2 C.sub.6 H.sub.4 --)-5-C.sub.6 H.sub.5 --        120)   4-C.sub.6 H.sub.5 -- 5-(2-CH.sub.3 O--5-CH.sub.3 C.sub.6 H.sub.3              --)                                                                    121)   4,5-(p-CH.sub.3 OC.sub.6 H.sub.4 --).sub.2                             122)   4-[2,4-(CH.sub.3 O).sub.2 C.sub.6 H.sub.3 --5-C.sub.6 H.sub.5 --]      123)   4-(3-HO.sub.3 S--4-CH.sub.3 OC.sub.6 H.sub.3 --)-5-C.sub.6 H.sub.5            --                                                                     124)   4-(3-ClO.sub.2 S--4-CH.sub.3 OC.sub.6 H.sub.3 --)-5-C.sub.6                   H.sub.5 --                                                             125)   4-(3-C.sub.2 H.sub.5 O.sub.3 S--4-CH.sub.3 OC.sub.6 H.sub.3                   --)-5-C.sub.6 H.sub.5 --                                               126)   4-(3-C.sub.6 H.sub.5 NHO.sub.2 S--4-CH.sub.3 OC.sub.6 H.sub.3                 --)-5-C.sub.6 H.sub.5 --                                               127)   4-(3-CH.sub.3 CO--4-CH.sub.3 OC.sub.6 H.sub.3 --)-5-C.sub.6                   H.sub.5 --                                                             128)   4-(3-C.sub.2 H.sub.5 CO--4-CH.sub.3 OC.sub.6 H.sub.3 --)-5-C.sub.6            H.sub.5 --                                                             129)   4-C.sub.6 H.sub.5 --5-(3-pyridyl-)                                     130)   4-C.sub.6 H.sub.5 --5-(4-pyridyl-)                                     131)   4-C.sub.6 H.sub.5 --5-(2-furyl-CH=CH--)                                132)   4-CH.sub.3 --5-CH.sub.3 O.sub.2 C--                                    133)   4-CH.sub.3 O.sub.2 C--5-C.sub.6 H.sub.5 --                             134)   4-C.sub.2 H.sub. 5 O.sub.2 C--5-C.sub.6 H.sub.5 --                     135)   4-C.sub.6 H.sub.5 --5-CH.sub.3 O.sub.2 C--                             136)   4-CH.sub.3 --5-[p-(CH.sub.3).sub.2 NC.sub.6 H.sub.4 N=CH--]            137)   4-C.sub.2 H.sub.5 --5-[p-(CH.sub.3).sub.2 NC.sub.6 H.sub.4                    N=CH--]                                                                138)   4-(n-C.sub.3 H.sub.7 --)-5-[p-(CH.sub.3).sub.2 NC.sub.6 H.sub.4               N=CH--]                                                                139)   4-C.sub.6 H.sub.5 --5-[p-(CH.sub.3).sub.2 NC.sub.6 H.sub.4                    N=CH--]                                                                140)   4-CH.sub.3 --5-[p-(CH.sub.3).sub.2 NC.sub.6 H.sub.4.sbsb.o                    N=CH--]                                                                141)   4-C.sub.2 H.sub.5 --5-[p-(CH.sub.3).sub.2 NC.sub.6 H.sub.4.sbsb.o             N=CH--]                                                                142)   4-(n-C.sub.3 H.sub.7 --)-5-[p-CH.sub.3).sub.2 NC.sub.6 H.sub.4                .sbsb.oN=CH--]                                                         143)   4-C.sub.6 H.sub.5 --5-[p-(CH.sub.3).sub.2 NC.sub.6 H.sub.4.sbsb.o             N=CH--]                                                                144)   4-HS--5-C.sub.6 H.sub.5 --                                             145)   4-HS--5-(p-CH.sub.3 OC.sub.6 H.sub.4 --)                               146)   4-CH.sub.3 S--5-C.sub.6 H.sub.5 --                                     147)   4-CH.sub.3 S--5-(p-CH.sub.3 OC.sub.6 H.sub.4 --)                       148)   4-CH.sub.3 COS--5-C.sub.6 H.sub.5 --                                   149)   4-CH.sub.3 COS--5-(p-CH.sub.3 OC.sub.6 H.sub.4 --)                     150)   4-C.sub.6 H.sub.5 COS--5-C.sub.6 H.sub.5 --                            151)   4-C.sub.6 H.sub.5 COS--5-(p-CH.sub.3 OC.sub.6 H.sub.4 --)              152)   4-CH.sub.3 O--5-C.sub.6 H.sub.5 --                                     __________________________________________________________________________

1,2-dithiole-3-thiones can be converted to 1,2-dithiolium compounds byoxidizing 1,2-dithiole-3-thiones. Any convenient method of oxidation canbe employed.

The preferred method of preparation depends on the particular thione tobe oxidized. For example, where the thione yields an unstable dithioliumcompound, it is desirable to precipitate the dithiolium salt fromsolution so that it does not decompose. This is done by precipitatingthe thiolium as an insoluble salt so it will not be decomposed byfurther oxidation. For example, aryl thiones when converted to thecorresponding dithiolium compounds are unstable to further oxidation buttheir decomposition can be prevented by precipitation from solutionduring oxidation as insoluble salts.

My Application Ser. No. 79,709, filed Oct. 9, 1970, now abandoned,discloses that non-aryl substituted such as aliphatic dithiole-thioneswhen converted to the corresponding dithiolium compounds yield stablecompounds which are not subject to further oxidative decomposition.Therefore, it is not as important to precipitate such dithioliumcompounds from solution as insoluble salts.

Application Ser. No. 79,709 further discloses that, in general, thealiphatic dithiolium compounds are also more water soluble than the aryldithiolium compounds. For example, certain aliphatic dithioliumcompounds are at least 75% water soluble in contrast to the less than10% solubility of the aryl dithiolium compounds. Thus aliphaticdithiolium compounds are not only more soluble but are also more stablethan the aryl compounds.

Application Ser. No. 79,709 further discloses that because of their highaqueous solubility and stability the aliphatic dithiolium compounds areparticularly useful as corrosion inhibitors in aqueous and/or aeratedand/or acidic systems.

A wide variety of oxidizing agents can be employed, as illustrated bythe following:

1. aqueous solution of hydrogen peroxide

2. hydrogen peroxide and an organic or inorganic acid

3. barium permanganate

4. t-butyl-hydroperoxide

5. m-chloroperbenzoic acid

6. Caro's acid

7. Peracetic acid

8. Potassium persulfate

9. chromic anhydride

10. perchloric acid, etc.

11. other oxidation agents can also be employed.

The choice of oxidizing agent will depend on the particular thione to beoxidized, economics, etc.

In general, the thione is oxidized in a suitable solvent at as low atemperature consistent with a reasonable reaction time so as to minimizeside reactions. The particular reaction time will depend on theparticular thione, the particular oxidizing agent, etc.

In practice reaction times of from 0.5 hours to 24 or more hours areemployed; with hydrogen peroxides shorter time can be employed such asfrom about 1-2 hours. With milder oxidizing agents such as organicperoxides longer times may be employed such as 24 hours withchloroperbenzoic acid.

Any solvent that does not interfere with the reactants and products canbe employed for example; water, methanol, ethanol, 1-propanol, butanol,acetone, dimethyl sulfamide, dimethyl formamide, ether tetrahydrofuran,chloroform, carbon tetrachloride, etc.

In general, room temperature or lower is preferably employed to reduceside reactions. Higher temperatures may be employed in oxidizing certainthiones such as about 50°C. or higher in certain instances.

Although Ser. No. 79,709 discloses the oxidation of thiones, dithioliumcompounds can be prepared by other methods such as for example by thosedescribed in "Advances in Heterocyclic Chemistry", Katritzby, et al.,Vol. 7, 1966, published by Academic Press, pp 39-151, which isincorporated herein as if part thereof.

The following Examples are presented by way of illustration and not oflimitation.

EXAMPLE 1B 3-t-Butyl-4-neopentyl-1,2-dithiolium hydrogen sulfate

In a 2 liter four necked round-bottom flask equipped with a mechanicalstirrer, a thermometer, a reflux condenser and an addition funnel wasplaced a mixture of 260 grams of4-neopentyl-5-t-butyl-1,2-dithiole-3-thione and 500 cc of glacial aceticacid. The mixture was cooled to 15°C. and 258 grams of 30% hydrogenperoxide was added at such a rate that a reaction temperature of15°-25°C. was maintained (two hours). After the addition was completed,the mixture was stirred for an additional 2 hours at room temperature.The solvents were distilled off under diminished pressure. The remainingsolid was washed with acetone and filtered to yield 258 grams (80% oftheory) of 3-t-butyl-4-neopentyl-1,2-dithiolium hydrogen sulfate as alight yellow solid, m.p. 189°-190°C; u.v.λ max.^(H).sbsp.2O (E) 254 mμ(5,000) and 306 mμ (6,800); nmr (solvent D₂ O) τ in ppm, internalstandard t.m.s., - 0.03 (s., 1H), 6.74 (s., 2H), 8.22 (s., 9H) and 8.88(s., 9H).

Anal. Calced. for C₁₂ H₂₂ O₄ S₃ : C, 44.14; H, 6.74; S, 29.43. Found: C,43.98; H, 6.82; S, 29.8.

EXAMPLE 2B 3-t-Butyl-4-neopentyl-1,2-dithiolium perchlorate (HSO₄ ⁻ →ClO₄ ⁻)

To a solution of 5 grams of 3-t-butyl-4-neopentyl-1,2-dithioliumhydrogen sulfate in 5 grams of distilled water was added 4 cc of 70%perchloric acid. The white solid which precipitated was filtered anddried to yield 5 grams (100%) of material, m.p. 157°-158°C; u.v.λmax^(EtOH) (E) 254 mμ (4,780) and 307 mμ (5,010).

Anal. Calced. for C₁₂ H₂₁ S₂ ClO₄ : S, 19.5. Found: 2, 19.4.

EXAMPLE 3B 3-t-Butyl-4-neopentyl-1,2-dithiolium hydrogen sulfate

The product was prepared in 80% of the theoretical yield according to aprocedure identical as in Example 1B, with the exception that instead ofacetic acid as the solvent, a mixture of 50 g of acetic acid and 450 gof isopropanol as the solvent was employed.

EXAMPLE 4B 3-t-Butyl-4-neopentyl-1,2-dithiolium hydrogen sulfate

To a sample of 5.2 grams of 4-neopentyl-5-t-butyl-1,2-dithiole-3-thionedissolved in 100 grams of chloroform was added a solution of 12.2 gramsof m-chloroperbenzoic acid (85%) in 200 grams of chloroform. The mixturewas allowed to stand for 24 hours at room temperature. The chloroformsolution was evaporated under diminished pressure and the remainingsolid extracted with 100 cc of distilled water. The aqueous solution wasdistilled under diminished pressure to yield 4.8 grams (73% of theory)of Example 1B.

EXAMPLE 5B 4-Phenyl-1,2-dithiolium hydrogen sulfate

This product was prepared in 80% yield from4-phenyl-1,2-dithiole-3-thione according to the procedure described inExample 4B. Bright yellow solid m.p. 230°-232°C. (dec.); u.v.λmax.^(H).sbsp.2O (E) 242 mμ (15,400) and 345 mμ (1,700), nmr (solvent D₂O) in ppm, internal standard t.m.s., -0.06 (s., 2H) and 2.05-2.51 (m.,5H).

Anal. Calced. for C₉ H₈ O₄ S₃ : C, 39.1; H, 2.9; S, 34.8. Found: C,38.8; H, 3.1; S, 34.9.

EXAMPLE 6B 3-(p-methoxy phenyl) - 1,2 thiolium hydrogen sulfate

The desired product was obtained in a 40% yield, according to theprocedure described in Example 1B, as an orange solid, m.p. 195°-196°C.(dec.), after crystallization from ethanol; u.v.λ max.^(H).sbsp.2O (E)244 mμ (7,100) and 411 mμ (23,300).

Anal. Calced. for C₁₀ H₁₀ O₅ S₃ : C, 39.2; H, 3.3; S, 31.4. Found: C,39.1; H, 3.1; S, 31.2.

The formulae of the above dithiolium compounds are presented in thefollowing Table.

                  TABLE II                                                        ______________________________________                                        Ex.   R (3)            R' (4)      X                                          ______________________________________                                              CH.sub.3         CH.sub.3                                                     |       |                                             1B    CH.sub.3 --C--   CH.sub.3 --C--CH.sub.2 --                                                                 H SO.sub.4                                       |       |                                                   CH.sub.3         CH.sub.3                                                     CH.sub.3         CH.sub.3                                                     |       |                                             2B    CH.sub.3 --C--   CH.sub.3 --C--CH.sub.2 --                                                                 Cl O.sub.4                                       |       |                                                   CH.sub.3         CH.sub.3                                               3B    Same as Example 1                                                       4B    Same as Example 1                                                       5B    H                            H SO.sub.4                                 6B                     H           H SO.sub.4                                 ______________________________________                                    

The reaction may be summarized as follows: ##SPC2##

The anion employed will depend on the properties desired for examplesolubility, insolubility, partial solubility. Example of anions includesulfates, bisulfates, sulfites, bisulfites, halides, i.e., Cl, Br, I, F,etc., phosphates, phosphites, etc., chlorates, etc. In addition toemploying the salts, quaternaries can be employed so that the hydrogenin the 5 position R'' is for example alkyl, aryl, etc. ##SPC3##

Any suitable quaternizing agent may be employed, for example,

1. alkyl halides such as methyl iodide, butyl iodide, butyl bromide,etc.

2. Sulfuric acid and derivatives H₂ SO₄, R₂ SO₄ where R is alkyl, etc.,methyl, ethyl, etc. for example (Me)₂ SO₄

3. alkyl thioureas such as methyl thiourea, etc.

4. Sulfonate esters, for example ##SPC4##

where R is alkyl such as methyl, etc., and R is hydrogen, alkyl, etc.,for example, methyl p-toluene sulfonates.

5. Alkyl phosphates, e.g. (MeO)₃ PO, (EtO)₃ PO, etc.

It is to be noted that where the anion is polyfunctional, such asdifunctional, 2 moles of the dithiolium would be coupled with one moleof the anion, for example ##SPC5##

such as where X is sulfate, a dicarboxylic acid such as phthalic acid,etc., for example ##SPC6##

, etc.

Polyfunctional quaternaries may also be formed, for example ##SPC7##

such as where A is alkylene, ##SPC8##

--(CH₂ CH₂)₂ O, --CH₂ --CH=CH--CH₂ --, etc.

I have now discovered a process of reacting the dithiolium compoundsdescribed herein with phosphite esters under basic conditions to formthiophosphates of the formula ##EQU7## where X is O or S, R is ahydrocarbon or a substituted hydrocarbon group such as alkyl, aryl,cycloalkyl, aralkyl, alkaryl, etc., and R' is a 3-thione-propene-1 or asubstituted 3-thione-propene-1 group. I have also discovered that theprocess can be reversed to the original dithionium compound by reactingthe thiophosphate product under acid conditions.

The overall reaction can be summarized by the following equations whereB is a base. In the following equations the phosphite ester can also bea thiophosphite, or a mixed oxygenthiophosphite, i.e., ##EQU8## where Xis O or S. Thus all X's may be oxygen or sulfur or both oxygen andsulfur. Corresponding thiophosphates will be formed. pg,23 ##SPC9##

The reversed reaction is given by the equation: ##SPC10##

The products obtained are IV and/or V and/or VI and/or VII.

Since the starting material can be represented by the two extremeresonance structures: ##SPC11##

two different phosphor-sulfur bonds can be formed if R₁ ≠ R₃ and sinceeach product formed can exist as two isomers a total of four products ispossible.

The formation of IV, V, VI and VII will depend upon the nature of R₁,R₂, and R₃ groups and of the phosphite used.

The dithiolium compounds described herein as well as others can bereacted under basic conditions with phosphites to form themonothiophosphates.

In general the reaction is carried out by reacting one mole of thedithiolium compound with at least 1 mole of phosphite at ambienttemperature, such as from about -10° to 60°C, but preferably at aboutroom temperature, i.e., from 0° to about 30°C.

The phosphites employed in this invention are of the formula ##EQU9##where R is an alcohol moiety, for example, alkyl, aryl, cycloalkyl,aralkyl, alkaryl, and substituted derivatives thereof, but preferablywhere R is alkyl, for example, C₁ to C₁₈ or higher, and most preferablylower alkyl, i.e., C₁ to C₈.

In addition, the oxygen phosphites, corresponding thiophosphite or mixedoxygen thiophosphites can be employed, for example, of the generalformula ##EQU10## where X is oxygen or sulfur, for example, ##EQU11##

Any basic material capable of promoting the reaction can be employed.These include alkali metal and alkaline earth metal hydroxides, oxides,alkoxides, and also salts of these metals with weak, inorganic andorganic acids, for example, those derived from Group IA and IIA of theperiodic table.

As examples of the alkali metal and alkaline earth metal hydroxides,there may be mentioned sodium hydroxide, potassium hydroxide, lithiumhydroxide, calcium hydroxide, barium hydroxide, strontium hydroxide, andmagnesium hydroxide. The alkoxides are represented by sodium n-butoxide,and the corresponding potassium lithium, calcium, strontium, barium andmagnesium alcoholates.

The preferred basic material comprises amines. Although a wide varietyof amines can be employed such as primary, secondary, tertiary, mono andpolyamines, in order to reduce side reactions tertiary amines areemployed, preferably volatile tertiary monoamines that can be easilyremoved on completion of the reaction, for example tertiary amines ofthe formula ##EQU12## where the R's, which may be the same or different,are hydrocarbon, preferably alkyl and most preferably lower alkyl, forexample, where the R's are methyl, ethyl, propyl, butyl, pentyl, hexyl,heptyl, etc., where the alkyls are straight chained, branched, etc.

Ammonia can also be employed, i.e., where the R's are hydrogen.

In general, sufficient base is employed to remove the anion so as torender the system basic, i.e., at least one equivalent of base per moleof dithiolium compound.

The anion X⁻ may be stated herein in relation to the dithioliumcompound, for example halides (Cl, Br, I, F) chlorates, carboxylates,such as derived from aliphatic acids, for example acetates, propionates,etc., aromatic acids, for example benzoates, salicylates, phthalates,etc., phosphates, sulfates, sulfonates, etc.

The thiosphophate can be reconverted to the dithiolium compound byadding a sufficient amount of an acidic material to render it acidic,thus reverting it to the cationic form. To achieve this at least oneequivalent of acid is added per mole of dithiole. The acidic materialcan be organic or inorganic, for example, hydrohalic acids such as HCl,HBr, etc., sulfuric, phosphoric, sulfonic acids, etc.; organic acidssuch as the alkyl, aryl, cycloalkyl, alkaryl, aralkyl, heterocyclic,etc., carboxylic acids, for example acetic, proprionic, butyric, etc.,fatty acids such as stearic, oleic, palmitic, etc., acids, benzoic,phthalic, etc., acids.

The following examples are presented for purposes of illustration andnot limitation.

EXAMPLE 1C O,O'-Dimethyl-S-(2-Neopentyl-4,4-dimethyl-3-thione-pentene-1)monothiophosphate

To a mixture of 16.4 grams of 3-tertiary-butyl-4-neopentyl-1,2dithiolium perchlorate (Ex. 2B) and 19.0 grams of the dimethylphosphitewas added 7.3 grams of triethylamine. After the addition oftriethylamine was completed, there was added 100cc of ether and 50 cc ofwater. The etheral layer was separated and washed several times withwater. After the ether solution was dried over anhydrous magnesiumsulfate, the ether was distilled off under diminished pressure. Therewas isolated 16.5 grams (97% of theory) ofo,o'-dimethyl-S-(2-neopentyl-4,4-dimethyl-3-thione-pentene-1)monothiophosphate as a red-purple solid, melting point 69°-71°C; n.m.r.(solvent CCl₄), τ in ppm, 4.13, 1 H doublet (J = 9 cps, vinyl); 6.31, 6H doublet (J = 13 cps, methoxy); 7.66, 2 H singlet (CH₂ neopentyl);8.63, 9 H singlet (t-butyl), and 9.08, 9 H singlet (t-butyl).

Anal. calculated for C₁₄ H₂₇ O₃ PS₂ : P, 9.17; S, 19.0.

Found : P, 9.05, S, 20.1.

EXAMPLE 2C O,O'-Dimethyl-S-(2-Neopentyl-4,4-dimethyl-3-thione-pentene-1)monothiophosphate

A mixture of 15 grams of 3-tertiary-butyl-4-neopentyl-1,2dithioliumhydrogen sulfate (Ex. 1B) and 15 grams of dimethyl phosphite dissolvedin 50 grams of water was treated slowly with 10 grams of 29% ammoniumhydroxide solution. The product which precipitated was filtered off andwashed with water. After drying in vacuo, there was isolated 13.5 gramsof o,o'-dimethyl-S-(2-neopentyl-4,4-dimethyl-3-thione-pentene-1)monothiophosphate (86% of theory) in all respects identical to theproduct isolated as described in Example 1C.

EXAMPLE 3C O,O'Diethyl-S-(2-Neopentyl-4,4-dimethyl-3-thione-pentene-1)monothiophosphate

A mixture of 6.0 grams of 3-tertiarybutyl-4-neopentyl-1,2 dithioliumperchlorate (Ex. 2B) and 3.73 grams of diethylphosphite in 30 cc ofether was treated with 2.73 grams of triethylamine. The etherealsolution was extracted several times with water. After the etherealsolution was dried over anhydrous magnesium sulfate, the ether wasdistilled off under diminished pressure. There was isolated 6.36 gramsof o,o'-diethyl-S-(2-neopentyl-4,4-dimethyl-3-thione-pentene-1)monothiophosphate (96% of theory) as a purple liquid; n.m.r. (solventCCl₄), τ in ppm, 4.03, 1 H doublet (J = 9 cps, vinyl); 5.88, 4 Hmultiplet (ethoxy); 7.61, 2 H singlet (neopentyl); 8.59, 9 H singlet(tertiarybutyl); 8.67, 6 H triplet (J = 7.5 cps, ethoxy); and 9.04, 9 Hsinglet (tertiarybutyl).

Anal. Calculated for C₁₆ H₃₁ O₃ PS₂ : P, 8.45; S, 17.5.

Found : P, 8.19, S, 18.3.

EXAMPLE 4CO,O'Diisopropyl-S-(2-Neopentyl-4,4-dimethyl-3-thione-pentene-1)monothiophosphate

In a fashion as described in Example 3C, there was reacted 6.0 grams of3-tertiary butyl-4-neopentyl-1,2 dithiolium perchlorate (Ex. 2B), 4.49grams of diisopropyl phosphite and 2.73 grams of triethylamine. Thereaction mixture was worked up in a manner as described in Example 3C toyield 7.1 grams (100% of theory) ofo,o'-diisopropyl-S-(2-neopentyl-4,4-dimethyl-3-thione-pentene-1)monothiophosphate as a purple liquid; n.m.r. (solvent CCl₄), τ in ppm,4.00, 1 H doublet (J = 10 cps, vinyl); 5.30, 2 H multiplet (isopropoxy);7.60, 2 H singlet (neopentyl); 8.59, 9 H singlet (tertiarybutyl); 8.67,12 H doublet (isopropoxy); and 9.03, 9 H singlet (tertiarybutyl).

Anal. Calculated for C₁₈ H₃₅ O₃ PS₂ : P, 7.90.

Found : P, 8.10.

EXAMPLE 5C O,O'-Di-n-butyl-S-(2-Neopentyl-4,4-dimethyl-3-thione-pentene-1)monothiophosphate

As described in Example 3C, there was reacted 6.0 grams of3-tertiarybutyl-4-neopentyl-1,2 dithiolium perchlorate (Ex. 2B), 5.24grams of di-n-butyl phosphite and 2.73 grams of triethylamine. There wasisolated 7.6 grams (100% of theory) of0,0'-di-n-butyl-S-(2-neopentyl-4,4-dimethyl-3-thione-pentene-1)monothiophosphate as a purple liquid; n.m.r. (solvent CCl₄), τ in ppm,4.03, 1 H doublet (J = 10 cps, vinyl); 5.92, 4 H multiplet (n-butyl);7.62, 2 H singlet (neopentyl); 8.12-9.30, 14 H multiplet (n-butyl); 8.599 H singlet (tertiarybutyl); and 9.05, 9 H singlet (t-butyl).

EXAMPLE 6C O,O'-Diphenyl-S-(2-Neopentyl-4,4-dimethyl-3-thione-pentene-1)monothiophosphate

To a mixture of 10.0 grams of 3-tertiarybutyl-4-neopentyl-1,2 dithioliumhydrogen sulfate (Ex. 1A) and 4.7 grams of diphenyl phosphite in 30 ccof ether was added 2.0 grams of triethylamine. The mixture was stirredfor 10 minutes and filtered. The ether was distilled off underdiminished pressure to yield 7.2 grams (78% of theory) of thesubstituted monothiophosphate as a viscous purple liquid. Upon standingfor one day the product changed into a pink solid, melting point75°-80°C. Crystallization from methanol yielded0,0'-diphenyl-S-(2-neopentyl-4,4-dimethyl-3-thione-pentene-1)monothiophosphate as yellow needles; melting point 97°-98°C; n.m.r.(solvent CCl₄), τ in ppm, 2.52-2.83, 10 H multiplet (phenyl); 5.27, 1 Hdoublet (J = 13.5 cps., vinyl); 7.30, 2 H multiplet (neopentyl); 8.81, 9H singlet (tertiarybutyl); and 8.96, 9 H singlet (tertiarybutyl).

Anal. Calculated for C₂₄ H₃₁ O₃ PS₂ : P, 6.75; S, 13.85.

Found : P, 6.54; S, 13.80.

EXAMPLE 7C 3-tertiarybutyl-4-neopentyl-1,2 dithiolium Perchlorate

A sample of 1.5 grams of0,0'-dimethyl-S-(2-neopentyl-4,4-dimethyl-3-thione-pentene-1)monothiophosphate was dissolved in 15 grams of methanol. To the solutionwas added 2.3 grams of 70% perchloric acid and 45 grams of water. Theprecipitate was filtered off and dried. The product was in all respectsidentical to 3-tertiarybutyl-4-neopentyl-1,2 dithiolium perchlorate asdescribed in Ex. 2B.

The corresponding product was obtained by treating0,0'-diethyl-S-(2-neopentyl-4,4-dimethyl-3-thione-pentene-1)monothiophosphate with 70% perchloric acid.

EXAMPLE 8C

A sample of 0.6 grams of0,0'-diphenyl-S-(2-neopentyl-4,4-dimethyl-3-thione-pentene-1)monothiophosphate dissolved in 19 grams of methanol was treated with 0.9grams of 70% perchloric acid. To the mixture was added 18 grams ofwater. The precipitate was filtered off and dried. There was isolated0.6 grams of the corresponding dithiolium compound of Ex. 2B.

The formulae of the monothiophosphates formed in the above examples arein the following Table.

                  Table III                                                       ______________________________________                                        Ex.     R.sub.1   R.sub.2   R.sub.3 R.sub.4                                   ______________________________________                                        1C      tert-Butyl                                                                              Neopentyl H       CH.sub.3                                  2C      tert-Butyl                                                                              Neopentyl H       CH.sub.3                                  3C      tert-Butyl                                                                              Neopentyl H       C.sub.2 H.sub.5                           4C      tert-Butyl                                                                              Neopentyl H       iso-C.sub.3 H.sub.7                       5C      tert-Butyl                                                                              Neopentyl H       n-C.sub.4 H.sub.9                         6C      tert-Butyl                                                                              Neopentyl H       Phenyl                                    ______________________________________                                    

Other monothiophosphates similarly prepared are presented in thefollowing Table

                  Table IV                                                        ______________________________________                                        Ex.  dithiolium starting                                                      No.  material     phosphite Product                                           ______________________________________                                         9C  3,5 Diphenyl 1,2-                                                                          dimethyl  O,O'-Dimethyl-S-                                       dithiolium per-                                                                            phosphite (1,3 diphenyl-3-thione-                                chlorate               propene-1) monthio-                                                           phosphate                                         10C  3,5 Diphenyl 1,2                                                                           diphenyl  O,O'-Diphenyl-S- (1,3                                  dithiolium per-                                                                            phosphite diphenyl-3-thione-                                     chlorate               propene-1) monothio-                                                          phosphate                                         11C  3-Phenyl-4-methyl                                                                          dimethyl  O,O'-Dimethyl-S-(2-                                    1,2-dithiolium                                                                             phosphite methyl-3-phenyl-3-                                     perchlorate            thione-propene-1)                                                             monothiophosphate                                 ______________________________________                                    

Since the thiophosphates in this invention are more soluble in organicsystems than the corresponding dithiolium compounds, they can be addedto the organic phase of the systems in greater concentrations than thedithiolium compounds. When the organic phase is brought into contactwith the acidic aqueous phase, the thiophosphate is converted to thedithiolium compound at the interphase and extracted into the aqueousphase in which it is more soluble. In this way there is a gradual andcontinuous transfer from one phase to another as it is converted to itsanti-corrosive form. Thus, the oil solubility of the thiophosphatefacilitates handling in oil systems and acid convertibility withsubsequent enhanced water solubility of the product transports thecorrosion inhibitor to the aqueous phase. In this way the corrosioninhibitor is stored in the organic phase until ready for use where itgradually migrates to the aqueous acidic corrosive system as required.

In addition, an organic solution or suspension of the thiophosphate canbe placed in contact with the metal, as a liquid, grease, etc., and asacid fumes or aqueous or aqueous acid vapors contact the system, thethiophosphate converts to the dithiolium compound which acts as acorrosion inhibitor as required.

USE IN FLUIDS FOR DRILLING WELLS

This phase of the invention relates to the use of the compounds of thisinvention as corrosion inhibitors in producing an improved drillingfluid useful in drilling oil and gas wells.

Fluids commonly used for the drilling of oil and gas wells are of twogeneral types: water-base drilling fluids comprising, for example, aclay suspended in water, and oil-base drilling fluids comprising, forexample, a clay or calcium carbonate suspended in mineral oil.

A third type of drilling fluid which as recently been developed is oneof oil-in-water or water-in-oil emulsion, for example, emulsions ofmineral oil in water or water in mineral oil formed by means ofemulsifiers such as sulfuric acid; Turkey-red oil; soaps of fatty acids,for example, sodium oleate; emulsoid colloids, for example, starch,sodium alginate, etc. Varying amounts of finely divided clay, silica,calcium carbonate, blown asphalt and other materials may be added tothese emulsions to improve their properties and control their weight.

I have now discovered that the compositions of this invention can beemployed as a corrosion inhibitor in drilling fluids.

USE IN AIR DRILLING

It has long been conventional practice in drilling deep bore holes tocirculate a drilling mud down through the drill stem and up through thebore hole between the wall of the bore hole and the drill stem for theremoval of chips or cuttings from the bore hole and to provide supportfor the wall of the bore hole. More recently, in the drilling of holesin which wall support provided by drilling mud is not employed, drillinghas been carried out with the use of air for chip removal. Such drillingis not only normally faster than mud drilling, but is indispensable inareas where the supply of water is limited or when drilling throughcavernous formations into which the drilling mud flows and becomes lost.

The increasing popularity of air or gas drilling has come about not onlybecause this method of drilling is frequently faster, as noted above,but for the additional reasons that the drill bits last longer, theprovision and handling of water under wide ranges of temperatureconditions is avoided, boring samples are easily observed when they arenot mixed with mud, and there is no loss involved as in the case of muddrilling when drilling through cavernous formations. Furthermore, promptremoval of water entering the hole maintains a dry hole and thelikelihood of wall collapse is thereby reduced.

In a typical air drilling operation there may be provided, for example,an up-flow of air in the bore hole having a velocity of the order of3,000 feet per minute. This flow of air upwardly through the bore hole,which is produced by air pumped downwardly through the drill stem,provides adequate removal of cuttings. The air is delivered to the drillstem at pressures of 20 to 60 lbs. per square inch and for dewatering orfor breaking obstructions, as will be hereinafter described, thepressures may be increased to 180 to 200 lbs. or more per square inch.

Air drilling operations are frequently hampered by the inflow of waterinto the bore hole when the drill bit is penetrating a water bearingstratum or when the bore hole has passed through a water bearing stratumthat has not been cased. Normally, if drilling proceeds uninterruptedlyboth before and during penetration into a water bearing stratum, theflow of air is sufficient to blow the water out of the bore hole alongwith the cuttings and drilling dirt. There are, however, two majorproblems encountered in air drilling when water is entering the borehole. The first problem occurs when there is a small inflow of watersufficient to cause a dampening of the cuttings which, under certainconditions, will then ball-up, clogging and sometimes jamming the drillbit. The second problem is encountered when there is a substantialamount of water remaining in the bottom of the bore hole during drillingcausing a sloughing of the side wall of the bore hole. This lattercondition may arise even though the water entering the bore hole isbeing blown out of the hole as fast as it enters. If there is asubstantial inflow of water or if there is a substantial flow of waterpast a region of the bore hole susceptible to this condition, the waterpassing that region of the bore hole may cause a sloughing of the sidewall.

The addition of foam forming materials to the air flow when air drillingis employed in conjunction with sufficient water to provide foaminggives rise to numerous advantages in drilling operations. The water maybe introduced either through a water bearing stratum being penetrated bythe drill bit or, alternatively, if the hole is dry, water may beintroduced from the surface of the earth through the drill stem inconjunction with the delivery of compressed air and foam formingmaterial through the drill stem to the drill bit. In either case thewater may be said to be existing in the bore hole, and drillingoperations are described in U.S. Pat. No. 3,130,798.

The amount of the compositions of the invention to be employed as acorrosion inhibitor can vary widely depending upon particular compounds,the particular system, the amounts of oxygen present, etc. I may employconcentrations of from about 0.5 to 5,000 p.p.m., such as from about 4to 4,000 p.p.m., for example from about 20 to 2,000 p.p.m., butpreferably from about 100 to 1,000 p.p.m. The optimum amount, to bedetermined in each instance, which will depend on function andeconomics, can be lesser or greater than the above amounts under properconditions.

USE IN BRINES

This phase of the invention relates to the prevention of corrosion insystems containing a corrosive aqueous medium, and most particularly insystems containing brines.

More particularly, this invention relates to the prevention of corrosionin the secondary recovery of petroleum by water flooding and in thedisposal of waste water and brine from oil and gas wells. Still moreparticularly, this invention relates to a process of preventingcorrosion in water flooding and in the disposal of waste water and brinefrom oil and gas wells which is characterized by injecting into anunderground formation an aqueous solution containing minor amounts ofcompositions of this invention, in sufficient amounts to prevent thecorrosion of metals employed in such operation. This invention alsorelates to corrosion inhibited brine solutions of these compounds.

When an oil well ceases to flow by the natural pressure in the formationand/or substantial quantities of oil can no longer be obtained by theusual pumping methods, various processes are sometimes used for thetreatment of the oil-bearing formation in order to increase the flow ofthe oil. These processes are usually described as secondary recoveryprocesses. One such process which is used quite frequently is the waterflooding process wherein water is pumped under pressure into what iscalled an "injection well" and oil, along with quantities of water, thathave been displaced from the formation, are pumped out of an adjacentwell usually referred to as a "producing well." The oil which is pumpedfrom the producing well is then separated from the water that has beenpumped from the producing well and the water is pumped to a storagereservoir from which it can again be pumped into the injection well.Supplementary water from other sources may also be used in conjunctionwith the produced water. When the storage reservoir is open to theatmosphere and the oil is subject to aeration this type of waterflooding system is referred to herein as an "open water floodingsystem."

Because of the corrosive nature of oil field brines, to economicallyproduce oil by water flooding, it is necessary to prevent or reducecorrosion since corrosion increases the cost thereof by making itnecessary to repair and replace such equipment at frequent intervals.

I have now discovered a method of preventing corrosion in systemcontaining a corrosive aqueous media, and most particularly in systemscontianing brines, which is characterized by employing the compositionsof this invention.

I have also discovered an improved process of protecting from corrosionmetallic equipment employed in secondary oil recovery by water floodingsuch as injection wells, transmission lines, filters, meters, storagetanks, and other metallic implements employed therein and particularlythose containing iron, steel, and ferrous alloys, such process beingcharacterized by employing in water flood operation the compositions ofthis invention.

This phase of the invention then is particularly concerned withpreventing corrosion in a water flooding process characterized by thefloding medium containing an aqueous or an oil field brine solution ofthese compounds.

In many oil fields large volumes of water are produced and must bedisposed of where water flooding operations are not in use or wherewater flooding operations cannot handle the amount of produced water.Most states have laws restricting pollution of streams and land withproduced waters, and oil producers must then find some method ofdisposing of the waste produced salt water. In many instances,therefore, the salt water is disposed of by injecting the water intopermeable low pressure strata below the fresh water level. The formationinto which the water is injected is not the oil producing formation andthis type of disposal is defined as salt water disposal or waste waterdisposal. The problems of corrosion of equipment are analogous to thoseencountered in the secondary recovery operation by water flooding.

The compositions of this invention can also be used in such waterdisposal wells thus providing a simple and economical method of solvingthe corrosion problems encountered in disposing of unwanted water.

Water flood and waste disposal operations are too well known to requirefurther elaboration. In essence, in the present process, the floodingoperation is effected in the conventional manner except that theflooding medium contains a minor amount of the compound of thisinvention, sufficient to prevent corrosion, in concentrations of about10 p.p.m. to 10,000 p.p.m., or more, for example, about 50 to 5,000p.p.m., but preferably about 15 to 1,500 p.p.m. The upper limitingamount of the compounds is determined by economic considerations. Sincethe success of a water flooding operation manifestly depends upon itstotal cost being less than the value of the additional oil recoveredfrom the oil reservoir, it is quite important to use as little aspossible of these compounds consistent with optimum corrosioninhibition. Optimum performance is generally obtained employing about1,000 p.p.m. Since these compounds are themselves inexpensive and areused in low concentrations, they enhance the success of a floodoperation by lowering the cost thereof.

In addition, these compounds are not sensitive to oxygen content of thewater and these are effective corrosion inhibitors in both open waterflooding systems and closed water flooding systems.

While the flooding medium employed in accordance with the presentinvention contains water or oil field brine and the compounds, themedium may also contain other materials. For example, the floodingmedium may also contain other agents such as surface active agents ordetergents which aid in wetting throughout the system and also promotethe desorption of residual oil from the formation, sequestering agentswhich prevent the deposition of calcium and/or magnesium compounds inthe interstices of the formation, bactericides which prevent theformation from becoming plugged through bacterial growth, tracers, etc.similarly, they may be employed in conjunction with any of the operatingtechniques commonly employed in water flooding and water disposalprocesses, for example five spot flooding, peripheral flooding, etc.,and in conjunction with other secondary recovery methods.

USE IN ACID SYSTEMS

The compounds of this invention can also be employed as corrosioninhibitors for acid systems, for example as illustrated by the picklingof ferrous metals, the treatment of calcareous earth formations, etc.,as described in the following sections.

USE AS PICKLING INHIBITORS

This phase of the invention relates to pickling. More particularly, theinvention is directed to a pickling composition and to a method ofpickling ferrous metal. The term "ferrous metal" as used herein refersto iron, iron alloys and steel.

To prepare ferrous metal sheet, strip, etc., for subsequent processing,it is frequently desirable to remove oxide coating, formed duringmanufacturing, from the surface. The presence of oxide coating, referredto as "scale" is objectionable when the material is to undergosubsequent processing. Thus, for example, oxide scale must be removedand a clean surface provided if satisfactory results are to be obtainedfrom hot rolled sheet and strip in any operation involving deformationof the product. Similarly, steel prepared for drawing must possess aclean surface and removal of the oxide scale therefrom is essentialsince the scale tends to shorten drawing-die life as well as destroy thesurface smoothness of the finished product. Oxide removal from sheet orstrip is also necessary prior to coating operations to permit properalloying or adherence of the coating to the ferrous metal strip orsheet. Prior to cold reduction, it is necessary that the oxide formedduring hot rolling be completely removed to preclude surfaceirregularities and enable uniform reduction of the work.

The chemical process used to remove oxide from metal surfaces isreferred to as "pickling." Typical pickling processes involve the use ofaqueous acid solutions, usually inorganic acids, into which the metalarticle is immersed. The acid solution reacts with the oxides to formwater and a salt of the acid. A common problem in this process is"overpickling" which is a condition resulting when the ferrous metalremains in the pickling solution after the oxide scale is removed fromthe surface and the pickling solution reacts with the ferrous basemetal. An additional difficulty in pickling results from the liberatedhydrogen being absorbed by the base metal and causing hydrogenembrittlement. To overcome the aforementioned problems in pickling, ithas been customary to add corrosion inhibitors to the pickling solution.

The present invention avoids the above-described problems in picklingferrous metal articles and provides a pickling composition whichminimizes corrosion, overpickling and hydrogen embrittlement. Thus thepickling inhibitors described herein not only prevent excessivedissolution of the ferrous base metal but effectively limit the amountof hydrogen absorption thereby during pickling. According to theinvention, a pickling composition for ferrous metal is provided whichcomprises a pickling acid such as sulfuric or hydrochloric acid and asmall but effective amount of the dithiol thione compound of thisinvention, for example at least about 5 p.p.m., such as from about 100to 5,000 p.p.m., but preferably from about 500 to 1,500 p.p.m.

Ferrous metal articles are pickled by contacting the surface (usually byimmersion in the pickling solution) with a pickling composition asdescribed to remove oxide from their surface with minimum dissolutionand hydrogen embrittlement thereof and then washing the ferrous metal toremove the pickling composition therefrom.

USE IN ACIDIZING EARTH FORMATIONS

The compositions of this invention can also be used as corrosioninhibitors in acidizing media employed in the treatment of deep wells toreverse the production of petroleum or gas therefrom and moreparticularly to an improved method of acidizing a calcareous ormagnesium oil-bearing formation.

It is well known that production of petroleum or gas from a limestone,dolomite, or other calcareous-magnesian formation can be stimulated byintroducing an acid into the producing well and forcing it into the oilor gas bearing formation. The treating acid, commonly a mineral acidsuch as HCl, is capable of forming water soluble salts upon contact withthe formation and is effective to increase the permeability thereof andaugment the flow of petroleum to the producing well.

The corrosion inhibitors were evaluated using sand blasted 1020 mildsteel coupons monitored by a polarization resistance meter, a Pairinstrument described in U.S. Pat. No. 3,406,101.

The acid was placed in a beaker and the coupons placed in the acid.Corrosion rates were measured at various time intervals and percentprotection calculated in the usual manner as follows: ##EQU13## where R₁is corrosion rate without inhibitor

R₂ is corrosion in presence of inhibitor.

The utility of the compositions of this invention is illustrated in thefollowing Table.

USE AS CORROSION INHIBITORS IN HIGHLY ACID SYSTEMS

                  Table V                                                         ______________________________________                                        H.sub.2 SO.sub.4 180 g per liter                                              Fe.sup.+.sup.+ as FeSO.sub.4 10 g per liter                                   Fe.sup.+.sup.+ as Fe(SO.sub.4).sub.3 10 g per liter                           Inhibitor concentration 1,000 p.p.m.                                          Product of                                                                              Time     Temp. °F                                                                           % protection                                   Example No.                                                                   ______________________________________                                        1C        24       200         98                                             1C        48       200         98                                             1C        72       200         98                                             1C        96       200         98                                             3C         1        74         97                                             5C         1        74         99                                             5C        17        74         99                                             ______________________________________                                    

                  Table VI                                                        ______________________________________                                        HCl 100 g per liter                                                           Fe.sup.+.sup.+ as FeCl.sub.2 100 g per liter                                  Inhibitor concentration 1,000 p.p.m.                                          Product of                                                                    Example No.                                                                             Time     Temp. °F                                                                           % Protection                                   ______________________________________                                        1C        24       175         96                                             1C        48       175         95                                             4C         1        74         97                                             4C        18        74         98                                             ______________________________________                                    

An important aspect of pickling inhibitors is that they should remaineffective in presence of dissolved ferrous ions (from dissolution of theoxide scale). The continued effectiveness of the present compositions isillustrated in the above table.

The compositions of this invention may also be added to other aqueousand/or oxygenated systems such as steam generating systems, watercirculating systems such as in cooling towers, in automobile radiators,in diesel locomotive engines, in boiler water, sea-water ship ballast,etc.

The term "dithiolium compounds" includes 1,2-dithiolium compounds andderivatives thereof such as salts, quaternaries, etc.

The amount of thiophosphate employed in treating the corrosive systemsof this invention will vary with the particular compound employed, theparticular system, the solids present in the system, the degree ofcorrosivity of the system, etc. A minor amount of the compound isgenerally employed sufficient to impart corrosion protection to thesystem. In general one employs concentration of trace amounts such asfrom about 1.0 p.p.m. to 10,000 p.p.m., for example from 5 to 5,000p.p.m., such as from 100 to 2,500 p.p.m., but preferably from 500 to2,000 p.p.m. In practice, concentrations of 1,000 ± 2000 p.p.m., areemployed.

As is quite evident, new thiophosphates of this invention will beconstantly developed which could be useful in this invention. It is,therefore, not only impossible to attempt a comprehensive catalogue ofsuch compositions, but to attempt to describe the invention in itsbroader aspects in terms of specific chemical names used would be toovoluminous and unnecessary since one skilled in the art could befollowing the description of the invention herein select a usefuldithiolethione compound. This invention lies in the use of suitablethiophosphates as corrosion inhibitors in aqueous and/or oxygenatedand/or acid systems and their individual compositions are important onlyin the sense that their properties can affect this function. Toprecisely define each specific useful thiophosphate and aqueous systemin light of the present disclosure would merely call for knowledgewithin the skill of the art in a manner analogous to a mechanicalengineer who prescribes in the construction of a machine the propermaterials and the proper dimensions thereof. From the description inthis specification and with the knowledge of a chemist, one will know ordeduce with confidence the applicability of specific thiophosphatessuitable for this invention by applying them in the process set forthherein. In analogy to the case of a machine, wherein the use of certainmaterials of construction or dimensions of part would lead to nopractical useful result, various materials will be rejected asinapplicable where others would be operative. I can obviously assumethat no one will wish to use a useless thiophosphate nor will be misledbecause it is possible to misapply the teachings of the presentdisclosure to do so. Thus, any thiophosphate or mixtures containing themthat can perform the function stated herein can be amployed.

Although the term monothiophosphate relates to the reaction product ofphosphite esters, it is understood that the present invention alsoincludes the use of thiophosphites as well as mixedoxygen-thiophosphites which react to yield polythiophosphates.

I claim:
 1. Thiophosphates of the formula ##EQU14## where X is O or S, Ris alkyl, aryl, cycloalkyl, aralkyl or alkaryl and R' is of the formula##SPC12##where R₁, R₂ and R₃ are hydrogen, alkyl, aryl, cycloalkyl,alkenyl, alkynyl, alkaryl, aralkyl, or heterocyclic groups.
 2. Thethiophosphates of claim 1 where R' is of the formula ##SPC13##
 3. Thethiophosphates of claim 2 which are monothiophosphates and R is alkyl oraryl, R₁ is tert-butyl, R₂ is neopentyl and R₃ is hydrogen.
 4. Themonothiophosphates of claim 3 where R is lower alkyl or phenyl.
 5. Themonothiophosphates of claim 4 where lower alkyl is methyl, ethyl,isopropyl or n-butyl.
 6. The thiophosphates of claim 2 where X is O. 7.The thiophosphates of claim 3 where X is O.
 8. The monothiophosphates ofclaim 4 where X is O.
 9. The monothiophosphates of claim 5 where X is O.10. The thiophosphates of claim 1 which are monothiophosphates, X is O,R is methyl or phenyl and R' is 1,3-diphenyl-3-thione-propene-1 or2-methyl-3-phenyl-3-thione-propene-1.